Computer networks can have a large number of physical servers interconnected with one another in an underlay network by routers, switches, bridges, or other network devices via wired or wireless network links. Each physical server can host multiple virtualized servers or virtual network functions interconnected with one another in one or more virtual overlay networks supported by the underlay network. Network nodes and network end points of the virtual overlay networks can exchange messages via the underlay network in accordance with one or more network protocols.